Process for producing synthetic zeolites with MFI structure

ABSTRACT

A process is described for producing synthetic zeolites useful as catalysts with a MFI structure, a Si/Al atomic ratio from about 8 to 45 to 1 and very small primary crystallites. A Si source, an Al source and an organic template are reacted with one another under hydrothermal conditions. The process is carried out in the presence of seed crystals with an average particle size from roughly 10 to 100 nm, preferably from 20 to 50 nm, prepared from an earlier batch of synthetic zeolites with a MFI structure, without separation from the mother liquor. The process further includes conversion by ion exchange of the zeolites into an H form. Moldings may also be produced by the addition of binders and optionally catalytically active base metal and/or precious metal components before or after the moldings are produced. The zeolites as claimed in the invention are characterized by the combination of the following features: (a) Si/Al atomic ratio 8 to 45:1 (b) Size of the primary crystallites roughly 0.01 to 0.05 microns; (c) Ratio between longest and shortest axis of the primary crystallites: roughly 1.0 to 1.5:1; 
         (d) Ratio between the intensity of the x-ray diffraction line with the highest intensity (D max =3.865±0.015) and the intensity of the x-ray diffraction lines of ZSM 11-zeolite (D max =11.15 angstroms); mordenite (D max =9.06 angstroms); α-cristobalite (D max =3.345 angstroms); and analcim (D max =4.83 angstroms)&gt;500:1.

CROSS REFERENCED TO RELATED APPLICATION

This application is a divisional application claiming priority fromapplication Ser. No. 10/111,651 which was filed on Sep. 3, 2002.

SPECIFICATION

The invention relates to a process for producing synthetic zeolites withMFI structure.

DE-A-109 608 660 described a process for producing caprolactam fromcyclohexanoneoxime in the gaseous phase using MFI catalysts withsymmetrically arranged OH groups on their surface. The crystallite sizeof the MFI catalysts is <5, preferably 0.05 to 0.5 microns. Thecatalysts are produced by hydrothermal synthesis using tetrapropylammonium bromide. There are no indications of the use of seed crystals.

EP-B-0 568 566 describes a process for producing essentially binder-freezeolites with a SiO₂/Al₂O₃ ratio of more than 80, at an elevatedtemperature. A zeolite aggregate which is bound to silicon dioxide isaged in an aqueous ionic solution which contains hydroxyl ions.Spherical crystallites with a diameter of <3 microns are obtained. Thereare no indications of the use of seed crystals.

EP-B-0 609 270 discloses a process for producing zeolites of the MFItype with a uniform crystal size in which (i) a source of particulatesilicon dioxide with an average diameter of 1 micron or less; (ii) seedcrystals of the MFI zeolite with an average diameter of 100 nm or lessin the form of a colloidal suspension; (iii) an organicstructure-directing agent (template); and (iv) a fluorine source and analkali metal source are reacted with formation of an aqueous syntheticmixture. The seed crystals are present in an amount from 0.05 to 1700ppm by weight of the synthesis mixture and the synthesis mixture has abasicity, expressed as a molar ratio of OH⁻/SiO₂, of less than 0.1. Thesynthesis mixture is left to crystallize. The crystals producedpreferably have an average diameter or an average length of 0.3 to 30microns. The seed crystals can be obtained for example by grindinglarger crystals into smaller crystals in a ball mill. According to theexamples the seed crystals are produced separately from silicic acid,TPAOH, NaOH and water. They do not contain aluminum oxide sincesilicalites are used as the seed crystals. The seed crystals areseparated from the mother liquor, washed separately until the wash waterhas a pH less than 10, and used as a “colloidal seed crystal suspension”ready for use.

EP-B-0 643 671 describes a crystalline tectosilicate-ZSM-5-zeolite whichconsists essentially of acicular agglomerates. The average ratio oflength to diameter of these agglomerates is at least 2.5, the averagelength of the agglomerates usually being on the order of 0.20 to 10microns, preferably 0.4 to 5 microns. The zeolite can be produced bycrystallizing the synthesis mixture which contains (i) a silicon dioxidesource; (ii) a source for aluminum, gallium, boron, iron, zinc orcopper; or (iii) a source for a monovalent cation; and (iv) an organicstructure control agent (template). The process is characterized in thatthe synthesis mixture originally contains 0.05 to 2000 ppm seed crystalsof a MFI zeolite with an average maximum dimension of not more than 100nm.

EP-A-0 753 483 describes a process for producing a MFI zeolite. Asynthesis mixture is formed which is free of the organic templates, witha molar composition which corresponds to that of the zeolites to beproduced and which contains the zeolite seed crystals with a maximumdimension of at most 100 nm. The seed crystal-containing synthesismixture is hydrothermally treated. It was found that the presence ofcolloidal seed crystals in the zeolite synthesis mixture makes anorganic template unnecessary. The crystallite sizes of the MFI zeolitesaccording to the examples are between 1.2 and 2.8 microns. Thecrystallites are coffin-shaped.

WO 97/25272 describes a process for producing a MFI zeolite with anonspherical crystal morphology. (a) An aqueous-alkali synthesis mixturewith a silicic acid source and an organic template is reacted with (b)an active synthesis mixture which represents either (i) an agedaqueous-alkali synthesis mixture with a silicic acid source and anorganic template or (ii) an active mother liquor which is derived froman aqueous synthesis mixture which was used for at least onecrystallization and from which the crystals formed were removed. Themixture of (a) and (b) is then hydrothermally treated in order toinitiate crystallization.

EP-A-0 753 485 discloses the use of zeolite seed crystals with aparticle size of at most 100 nm in order to accelerate the zeolitecrystallization during thermal treatment of a zeolite synthesis mixture.Thermal treatment lasts no longer than 24 hours. The synthesis mixturecontains at most 0.1% by weight seed crystals. A zeolite of the ZSM typeis produced. The seed crystals used are produced specially, i.e. theyare not contained in the mother liquor from a preceding synthesis. Sincethe seed crystals have left the mother liquor in which theycrystallized, they have lower reactivity.

EP-A-0-021 675 discloses a continuous process for. producing acrystalline zeolite with a “constraint index” between 1 and 11 and aSiO₂/Al₂O₃ ratio of more than 12. A mixture of sources of an alkalimetal oxide (R₂O), an aluminum oxide, a silicon oxide and water arereacted using controlled amounts of reactants. The reaction takes placeusing seed crystals from the zeolite which results as the product.

U.S. Pat. Nos. 5,174,977, 5,174,978, 5,174,981 and 5,209,918 disclosezeolites of the ZSM-5 type and processes for their production. The seedcrystals are specially produced seed crystals which do not originatefrom the mother liquor from a preceding synthesis.

Compared to this prior art, the object of the invention is to producesynthetic, phase-pure zeolites rich in aluminum with a MFI structure andspherical nanocrystalline crystallites.

This object is achieved as claimed in the invention by a process forproducing synthetic zeolites with a MFI structure, a Si/Al atomic ratiofrom about 8 to 45 to 1 and very small primary crystallites. A Sisource, an Al source and an organic template are reacted with oneanother under hydrothermal conditions. The Si/Al atomic ratio is about 9to 50 and the ratio between the longest and shortest axis of the primarycrystallites is about 1.0 to 1.5:1. The process is carried out in thepresence of seed crystals with an average particle size from roughly 10to 100 nm, preferably from 20 to 50 nm from an earlier batch withoutseparation of the crystals from the mother liquor.

The process as claimed in the invention compared to the prior art hasthe advantage that the seed crystals used need not be subjected toadditional treatment steps. The seed crystals remain in the favorable pHrange of >11 throughout the process. The especially high activity of theseed crystals is ensured by this measure.

To determine the particle size of the seed crystals the particles areseparated by means of a centrifuge from the mother liquor and are washedrepeatedly with acetone. The resulting product is dried and thenexamined with a scanning electron microscope. In doing so a particlesize from 20 to 50 nm was established. The particles were essentiallyspherical.

Preferably precipitated silicic acid is used as the Si source, sodiumaluminate as the Al source and tetrapropyl ammonium bromide as theorganic template.

Hydrothermal conversion is preferably carried out at a temperature fromabout 100 to 180° C., a pH from about 11 to 13, and at a weight ratiobetween the Si and Al source from roughly 2.95 to 26.5 to 1.

In a further treatment stage the reaction product is preferably driedand calcined.

The subject matter of the invention is also synthetic zeolites with aMFI structure which can be obtained using the process described aboveand which are characterized by the combination of the followingfeatures:

-   -   (a) Si/Al atomic ratio 8 to 45:1    -   (b) Size of the primary crystallites of about 0.01 to 0.05        microns;    -   (c) Ratio between longest and shortest axis of the primary        crystallites: of about 1.0 to 1.5:1;    -   (d) Ratio between the intensity of the x-ray diffraction line        with the highest intensity (D_(max)=3.865±0.015) and the        intensity of the x-ray diffraction lines of ZSM 11-zeolite        (D_(max)=11.15 angstroms); mordenite (D_(max)=9.06 angstroms);        α-cristobalite (D_(max)=3.345 angstroms); and analcim        (D_(max)=4.83 angstroms)>500:1.

One development of the process as claimed in the invention is that thereaction product is converted by ion exchange into the H form. Moldingsproduced with the addition of binders and optionally catalyticallyactive base metal and/or precious metal components are added before orafter the moldings are produced.

The synthetic zeolites as claimed in the invention can be used ascatalysts, especially the zeolites in H form (with or without coatingwith base metals and/or precious metals) as catalysts for acid-catalyzedreactions, oxidations, reductions and adsorptions.

These reactions comprise among others:

Catalytic cracking (FCC additive) and hydrocracking (also “dewaxing” bycareful hydrocracking);

Alkylations, for example of aromatics with olefins, alcohols, orhalogen-containing paraffins;

Alkylation of aromatics;

Alkylation of isoparaffins with olefins;

Transalkylation (of aromatics);

Disproportionating (for example, toluene disproportionating, etc);

Isomerization and hydroisomerization (for example, of paraffins,olefins, aromatics, xylene-isomerization, dewaxing, etc.);

Dimerization and oligomerization;

Polymerizations;

Etherification and esterification;

Hydration and dehydration;

Adsorption;

Condensation;

Oxidation;

Acetalization;

Dealkylation and cyclization;

Alkylation and hydrodealkylation (ethyl benzene to benzene);

Exhaust gas cleaning;

Acid-catalyzed reactions are disclosed for example in DE-A-4 405 876. Acatalyst based on a particulate acid-activated phyllosilicate is usedwhich has particles joined to one another by a binder.

In their use as catalysts, the products as claimed in the invention aregenerally in lump form, for example as extrudates, granulates, pellets,balls, honeycombs and other molded bodies.

To achieve a certain strength, generally an inorganic, organometallic ororganic binder is added to the masses for producing the moldings.Preferably silicic acid or aluminum hydroxide sols are used as theorganic binders. Furthermore, aluminates, titanates or phosphates aresuited. Especially suited are alkaline earth compounds which form poorlysoluble salts when reacted with acid. Strontium and barium compoundsyield better binders compared to the corresponding calcium compounds.

Furthermore, suitable inorganic binders are compounds of metals ofgroups IIIA (preferably Y₂O₃), IIIB (preferably B₂O₃, Al₂O₃ orAl(H₂PO₄)₃), IVA (preferably TiO₂ and ZrO₂), IVB (preferably oxides,carbides or nitrides of silicon, lanthanoids, preferably LaO₂ or CeO₂)or the actinoids (preferably ThO₂).

Inorganic binders can also be used as hydraulic binders, preferablycement or gypsum, or natural silicate binders, such as mullite or talc.

The organometallic binder can be a compound of formula Me(OR)_(n) or offormula Me(O—CO—R)_(n), in which Me is a metal with a valency of n and Ris an organic residue, for example an alkyl, aryl, aralkyl, alkaryl orheterocyclic residue.

The organic binder can be a natural, semisynthetic or synthetic polymeror a precursor thereof, which does not lose its binding properties underprocessing and/or application conditions. Examples are alkene(co)polymerizates, polycondensates, polyaddition compounds, siliconerubber, silicone resin, rubber, bone glue, casein, galalith, alginates,starch, cellulose, guar, carboxymethylcellulose, polyvinyl alcohol,polyacrylic or polymethacrylic compounds as well as addition orcondensation resins. In particular furan resins or phenolic resins canbe used.

Examples of binders are disclosed in DE-A-4 405 876.

Inorganic, organometallic and/or organic binders can be combined withone another as claimed in the invention in a suitable manner. Here itcan be advantageous to use at least some of the binders in theircolloidal form and/or in soluble form. Some binders can themselves becatalytically active.

The relative weight ratio between the selected zeolites with MFIstructure on the one hand and the binder on the other varies fromroughly 20 to 80% by weight. The zeolite with the MFI structure ispreferably present in an amount of more than roughly 50% by weight,especially more than 60% by weight.

The invention is explained by the following examples.

EXAMPLE 1 Production of Zeolites in Na Form

1.662 g of demineralized water, 5.24 g sodium hydroxide and 709.5 gsodium aluminate were heated to 80° C. with vigorous stirring until aclear solution was obtained which was then cooled to below 60° C.

20 liters of a mother liquor from an earlier batch which (analytically)contained 3.43% by weight SiO₂, 2.16% by weight Na₂O and 5.5% by weighttetrapropyl ammonium bromide (TPABr) were placed in a separate vessel.The mother liquor furthermore contained roughly 0.1% by weight seedcrystals with an average particle size from 20 to 50 nm. The seedcrystals had the following (analytic) composition SiO₂: 91.77% byweight, Al₂O₃ 3.49% by weight, atomic ratio Si/Al=26.4.

The mother liquor was diluted with roughly 6 liters of demineralizedwater, whereupon 1980 g TPABr and 6260 g precipitated silicic acid(silica VN3LCC-Degussa) were added. The mixture was stirred for 30 to 60minutes, whereupon 2380 g of the first solution were added.

The mixture was homogenized for roughly 30 to 60 minutes. The pH of thegel was 12.7.

The synthesis mixture was placed in a 40 liter autoclave which wasprovided with a stirring mechanism, and gradually heated to roughly 130°C., stirring having been done with a stirrer speed of roughly 73 rpm.The pressure rose during the reaction gradually from 2.5 to 3.5 bar dueto the decomposition of the TPABr.

After 20 hours, a first sample amount of 127 g in the form of a white,medium-viscosity suspension with a pH of 11.13 was removed. The samplewas easily filtered via filter paper on a suction filter and washed inbatches with 5×200 ml deionized water. The filter cake was dried for onehour at 120° C. A wide peak was detected by x-ray at a layer latticedistance (D) of 3.8720 angstroms, i.e. the product was essentially stillamorphous.

After 61 hours, 149 g of a second specimen in the form of a white,medium-viscosity suspension with a pH of 12.01 were removed. Thisspecimen was processed like the first specimen and showed an x-raydiffraction spectrum with a very pronounced peak at 3.8720 angstroms.The degree of crystallinity (peak area/background area) was 96.8%.

After 68 hours, synthesis was terminated and a third specimen, which wasprocessed in the same way as the first and the second specimen, showed adegree of crystallinity of 97.9%.

The remainder of the batch was filtered on larger suction filters, 23.0kg of filter cake and 12.47 kg of mother liquor having been obtained.The mother liquor had the following analysis: Si=0.82% by weight, Al=5ppm, Na=1.22% by weight, OH=1.16% by weight, Br=3.71% by weight,TPABr=8.2% by weight. The mother liquor contained roughly 0.1% by weightseed crystals with an average particle size of roughly 30-40 nm and hada pH of 12.25. The mother liquor was used for the following batches.

The filter cake was homogenized by intensive stirring for roughly 30minutes in 120 liters of deionized water, then allowed to sediment andthe supernatant was poured off. The residue was washed 8 times with 100liters of water at a time until a pH from 7.3 to 7.4 was obtained andthe last wash water had electrical conductivity of 130 μS. The entirewashing process lasted roughly 5 hours, 20.7 kg filter cake having beenobtained.

The filter cake was dried at 120° C. for 48 hours and granulated onscreen granulator (Alexander werk) to a particle size of <2.0 mm. Theyield of dry granulate was 6.3 kg.

The granulates were calcined in a layer thickness of 10 mm at 540° C.

The yield of calcined product was 5.75 kg.

Characterization:

L01 1000° C.=6.5%; Si=43.6%; Al=3.31%; Na=1.71%;

C=182 ppm; Fe=208 ppm; Ca=257 ppm.

The Si/Al ratio was 12.65, the BET surface (according DIN/66132) was 352m²/g and the crystallinity was 96.96%.

The proportion of foreign phases which occur in conventional zeolitesyntheses was determined by comparison of the intensities of the x-raydiffraction lines with the highest intensity, for mordenite(D_(max)=9.06 angstroms); analcim (D_(max)=4.83 angstroms); andα-cristobalite (D_(max)=3.345 angstroms). The ratio between theintensity of the x-ray diffraction line of the product as claimed in theinvention with the highest intensity (D_(max)=3.8720 angstroms) andthose of the three comparison peaks was >500:1. The product as claimedin the invention is therefore phase-pure.

From the product obtained, scanning electron microscope (REM)photographs were prepared, crystallites with an average particle size ofroughly 30 nm having been found.

The crystallites were essentially spherical, the ratio between the longand short axis having been roughly 1.0 to 1:1.5.

COMPARISON EXAMPLE 1

The procedure from example 1 was repeated with the difference that amother liquor with 3.3% by weight seed crystals with a particle size of0.1 to 1 micron was used. The number of seed crystals corresponded tothose in the mother liquor as in Example 1.

The test was stopped after 100 hours, since the product which had beenremoved from the autoclave showed no crystallinity (roughly comparableto the specimen removed after 20 hours in example 1).

EXAMPLE 2 Producing a Zeolite in H Form

To produce a zeolite in H form, 3300 g of the calcined product which wasobtained according to Example 1 was mixed in a 20 liter vessel with astirring mechanism with 14.88 liters of deionized water. The suspensionwas heated to 80° C. as it was stirred, whereupon 1624 g 37%hydrochloric acid were added. Stirring continued for one hour at 80° C.,whereupon the solid was allowed to sediment within 30 minutes. Thesupernatant solution was withdrawn, whereupon 14.88 liters of deionizedwater and 1624 g of 37% hydrochloric acid were added. The suspension washeated to 80° C. as it was stirred, and stirred for one hour at 80° C.Then the solid was allowed to sediment within 2 minutes. The supernatantwas withdrawn, and the residue was repeatedly washed with deionizedwater until the conductivity of the wash water was less than 100 μS. Theresidue was then filtered on a suction filter.

The washed filter cake was dried for 16 hours at 120° C., 2.92 kg of thedry product having been obtained. The dry product was calcined at 540°C. for 10 hours. The yield of calcined product in H form was 2.85 kg.

The product had the following properties.

Ignition loss: 6.7% by weight; Si=45.44% by weight; Al=2.71% by weight;Na=48 ppm; Fe=80 ppm; C=160 ppm.

The Si/Al ratio was 16.1 compared to 12.65 of the product according toExample 1. The difference was due to the fact that some of the aluminumwas dissolved out during acid treatment.

The degree of crystallinity was 95.2%. The location of the main peak(D_(max)=3.856 angstroms) had essentially not changed at all. Thedistribution of crystallite sizes and the axial ratio were essentiallyidentical to those of the product from Example 1.

EXAMPLE 3 Production of a Binder-Containing Granulate from Zeolites in HForm from Example 2

2200 g of the powder from Example 2 were stirred for roughly 25 minuteswith 3500 g of a 25% silicic acid sol (stirrer at 60 rpm) until aplastic mass was obtained. To adjust the rheology, 44 g ofhydroxymethyl-hydroxypropylcellulose (Na salt) were added to this mass,whereupon the mass was kneaded again for 10 minutes at 60 rpm. The masswas extruded using an extruder (Haendle PZVM8b) with a nozzle diameterof roughly 1.5 mm. The extrudates were cut into pieces 3 mm long.

The pieces of extrudate were subjected to ion exchange with ammoniumnitrate to remove the sodium content (from the cellulose derivative),2.44 kg of the extrudate pieces having been carefully stirred with 4.89liters of deionized water and 0.37 kg of ammonium nitrate at 20° C. overan interval of 1.5 hours.

After settling of the extrudate pieces, the supernatant solution waspoured off. The extrudate pieces were washed several times. After theeighth washing, the conductivity of the wash water was less than 70 μS.The extrudate pieces were dried for 16 hours at 120° C., the yieldhaving been 2.40 kg.

The dried product was calcined at 600° C. The yield of calcined productwas 2.35 kg.

The calcined product had the following properties:

Binder content 30% by weight SiO₂, Na content: 50 ppm;

remaining composition as according to Example 2:

Degree of crystallinity: 86.4%

Side crush strength: 1.8 kp/3 mm, determined with a Schleuniger model 6D

Bulk weight: 550 g/liter;

Pore volume (determined according to Hg intrusion method with aporosimeter 4,000)=0.36 cm³/g

Pore size distribution: >1750 nm=1.3%, 1750-80 nm=17.4%; 80 to 17nm=45.6%; 14 to 7.5 nm=26.7%.

Average pore radius: 4 nm

Specific surface area (BET) 328 m²/g

EXAMPLE 4 Coating the Granulate from Example 3 with Platinum

In 35 ml of distilled water, 0.287 g hexachloroplatinic acid(H₂PtCl₆=10% by weight) were dissolved while stirring. 100 g of thegranulates from Example 3 were poured into a test tube with thissolution onto the top and intensively shaken, so that all granulateswere uniformly wetted.

The impregnated granulates were dried for 16 hours at 120° C. and heatedwith a heat-up rate of 1° C./min in air to 450° C., whereupon thistemperature was maintained for another 5 hours.

COMPARISON EXAMPLE 2

According to the method described by S. Ernst and J. Weitkamp(Chem.Ing.-Tech; 63; 748; 1991) zeolite synthesis was done without atemplate (TPABr). The Si/Al atomic ratio in the synthesis mixture was35:1. The raw materials were the following chemicals: colloidal silicasol (Syton X30; Monsanto); distilled water; technical caustic sodaPrills (Hoechst); sodium aluminate (Riedel de Haen).

After a reaction time of 112 hours at 160° C. a MFI zeolite contaminatedwith ZSM-11 (D=3.81 angstroms) and α-cristobalite (D_(max)=4.041angstroms) was obtained (ratio of peak intensities 100:59.76 and100:32.52). In the example as claimed in the invention the foreign phaseproportions were below the detection limit of 100:0.2.

When examined using scanning electron microscopy, a primary crystallitesize of 0.5 to 2 microns was ascertained. The primary crystallites hadan average axial ratio of 2.5 to 1.

EXAMPLE 5 Producing Zeolites in Na Form

1664 g demineralized water, 226.8 g sodium hydroxide and 365 g sodiumaluminate were heated to 80° C. while being vigorously stirred until aclear solution was obtained which was then cooled to below 60° C.

22 kg of a mother liquor from an earlier batch which (analytically)contained 3.43% by weight SiO₂, 2.16% by weight Na₂O and 5.5% by weighttetrapropyl ammonium bromide (TPABr) were placed in a separate vessel.The mother liquor furthermore contained roughly 0.1% by weight seedcrystals with an average particle size from 20 to 50 nm. The seedcrystals had the following (analytic) composition: SiO₂: 91.77% byweight, Al₂O₃ 3.49% by weight, atomic ratio Si/Al=26.4.

The mother liquor was diluted with 4280 g of demineralized water,whereupon 1881 g TPABr and 6209 g precipitated silicic acid (silicaFK320-Degussa) were added. The mixture was stirred for 30 to 60 minutes,whereupon 2247 g of the first solution were added.

The mixture was homogenized for roughly 30 to 60 minutes. The pH of thegel was 12.7.

The synthesis mixture was placed in a 40 liter autoclave which wasprovided with a stirring mechanism, and gradually heated to roughly 130°C., stirring having been done with a stirring speed of roughly 73 rpm.The pressure rose during the reaction gradually from 2.6 to 3.1 bar dueto the decomposition of the TPABr.

After 63 hours, a first sample amount of 143 g in the form of a white,medium-viscosity suspension with a pH of 12.05 was removed. The samplewas easily filtered via filter paper on a suction filter and washed inbatches with 5×200 ml deionized water. The filter cake was dried for onehour at 120° C. X-ray examination of the specimen showed a pronouncedpeak at 3.87 angstroms. The degree of crystallinity (peakarea/underlying area) was 97.9%.

After 80 hours, synthesis was terminated and a second specimen, whichwas processed in the same way as the first, showed likewise a degree ofcrystallinity of 97.9%.

Most of the batch was filtered on a suction filter, 16.7 kg of filtercake and 19.5 kg of mother liquor having been obtained. The motherliquor was not examined in detail.

The filter cake was homogenized by intensive stirring for roughly 30minutes in 120 liters of deionized water, then allowed to sediment andthe supernatant was poured off. The residue was washed 7 times with 100liters of water at a time until a pH from 7.7 to 7.8 was obtained andthe last wash water had electrical conductivity of 170 μS. The entirewashing process lasted roughly 6 hours, 16.35 kg of filter cake havingbeen obtained.

The filter cake was dried at 120° C. for 48 hours and granulated onscreen granulator (Alexander werk) to a particle size of <2.0 mm. Theyield of dry granulates was 6.1 kg.

The granulates were calcined in a layer thickness of 10 mm at 540° C.

The yield of calcined product was 5.4 kg.

Characterization:

L01 1000° C.=5.9% by weight; Si=44.8% by weight; Al=1.86% by weight;Na=0/56% by weight; C=201 ppm

The Si/Al ratio was 23.1, the BET surface (according DIN/66132) was 379m²/g and the crystallinity was 97.8%.

X-ray examination yielded no indication of foreign phases such asmordenite, analcim, or ZSM-11.

From the product obtained, scanning electron microscope (REM)photographs were prepared, crystallites with an average particle size ofroughly 30 nm having been found. The crystallites were essentiallyspherical, the ratio between the long and short axis having been roughly1.0 to 1:1.5.

EXAMPLE 6 Producing Zeolites in H Form

To produce a zeolite in H form, 2750 g of the zeolites producedaccording to Example 5 were mixed in a 20 liter vessel with a stirringmechanism with 12.4 kg of deionized water. The suspension was heated to80° C. as it was stirred, whereupon 1356 g 37% nitric (62%) were added.After stirring for one hour at 80° C., the stirring device was turnedoff and the solid was allowed to sediment. The supernatant solution waswithdrawn and the residue washed with several portions of deionizedwater until the conductivity of the wash water was 100 μS. The residuewas then filtered on a suction filter.

The washed filter cake was dried for 16 hours at 120° C., 2.625 kg ofthe dry product having been obtained. The dried product was calcined at540° C. for 10 hours. The yield of calcined product in H form was 2.580kg.

The product was characterized as follows:

Ignition loss: 3.9% by weight; Si=44.18% by weight;

Al=1.62% by weight; Na=94 ppm.

The Si/Al ratio was 26.2.

The crystallinity was 98.6%. The location of the main peak(D_(max)=3.856 angstroms) had essentially not changed at all. Thedistribution of crystallite sizes and the axial ratio were alsoessentially identical to those of the product from Example 1.

EXAMPLE 7 Production of a Binder-Containing Granulate from Zeolites in HForm from Example 6

2500 g of the zeolite powder from Example 6 were mixed with 734 g of aboehmite powder (aluminum oxide). 203 g of concentrated acetic acid and2400 g of deionized water were added to this mixture. Upon furthermixing a plastic mass formed. This plastic mass was mixed for another 30minutes before it was extruded using a Haendle extruder of type PZVM8bwith a nozzle diameter of roughly 1.5 mm. The extrudates were cut intopieces 3 mm long.

The pieces of extrudate were dried at 120° C. for 16 hours and thencalcined for 5 hours at 600° C.

The resulting product had the following properties:

Binder content 20% by weight Al₂O₃; remaining composition as accordingto Example 6:

Crystallinity: 95.0%

Side crush strength: 5.4 kp/3 mm, determined with a Schleuniger model 6D

Bulk weight: 591 g/liter;

Pore volume (determined according to Hg intrusion method with aporosimeter 4,000)=0.36 cm³/g

Pore size distribution: >1750 nm=0.3%, 1750-80 nm=1.4%; 80-17 nm=14.8%;14-7.5 nm=83.3%.

Average pore radius: 6 nm

Specific surface area (BET)=330 m²/g

APPLICATION EXAMPLE 1 Use of Platinum-Free Catalyst According to Example3 for Isomerization of m-Xylene and Hydrodealkylation of Ethyl Benzene(EB) to Benzene

A stainless steel reactor 610 mm long with an inside diameter of 19 mmand electrical jacket heating was filled with 15 ml of the catalyst fromExample 3 (diluted with 15 ml inert glass beads).

Activation is done at 300° C. for 12 hours under pure hydrogen(>99.95%). A defined hydrocarbon mixture of the composition describedbelow is passed over the catalyst bed according to the operatingconditions described below (test conditions) together with pure hydrogen(>99.95%). The composition of the product flow is determined by gaschromatography. The conversion of ethyl benzene (EB), xylene loss andconcentration of p-xylene compared to the thermodynamic equilibriumvalue (p-xylene approach to equilibrium, PXATE) are computed:Composition of the hydrocarbon mixture (HC): Ethyl benzene (EB) 15% byweight m-Xylene 85% by weight Test conditions: Temperature 400° C.Pressure 28 barg Space velocity LHSV 5.0 l/l/h H₂/HC 2.0 mole/moleRunning time 11 hours Catalyst performance: EB conversion 85.0% byweight Xylene loss 28.1% by weight PXATE 97.7% by weightComputation:EB conversion % = (EB in − EB out) × 100/EB in Xylene los % = (Totalxylenes in − total xylenes out) × 100/total xylenes inPXATE = (p-xylene isomer in the product normalized × 100/p-xylene isomerequilibrium)

APPLICATION EXAMPLE 2 Use of the Platinum-Containing Catalyst accordingto Example 4 for Xylene-Isomerization of m-Xylene and Hydrodealkylationof Ethyl Benzene (EB) to Benzene

A stainless steel reactor 610 mm long with an inside diameter of 19 mmand electrical jacket heating was filled with 15 ml of the catalyst fromExample 4 (diluted with 15 ml inert glass beads).

Activation is done at 300° C. for 12 hours under pure hydrogen(>99.95%).

A defined hydrocarbon mixture of the composition described below ispassed over the catalyst bed according to the operating conditionsdescribed below (test conditions) together with pure hydrogen (>99.95%).The composition of the product flow is determined by gas chromatography.The conversion of ethyl benzene (EB), xylene loss and concentration ofp-xylene compared to the thermodynamic equilibrium value (p-xyleneapproach to equilibrium, PXATE) are computed. Composition of thehydrocarbon mixture (HC): Ethyl benzene (EB) 15% by weight m-Xylene 85%by weight Test conditions: Temperature 400° C. Pressure 28 barg Spacevelocity LHSV 5.0 l/l/h H₂/HC 2.0 mole/mole Running time 15 hoursCatalyst performance: EB conversion 96.0% by weight Xylene loss 14.5% byweight PXATE 89.1% by weight

APPLICATION EXAMPLE 3 Use of Platinum-Containing Catalyst according toExample 4 for Isomerization of m-Xylene and Hydrodealkylation of EthylBenzene (EB) to Benzene

A stainless steel reactor 610 mm long with an inside diameter of 19 mmand electrical jacket heating was filled with 15 ml of the catalyst fromExample 4 (diluted with 15 ml inert glass beads).

Activation is done at 300° C. for 12 hours under pure hydrogen(>99.95%).

A defined hydrocarbon mixture of the composition described below ispassed over the catalyst bed according to the operating conditionsdescribed below (test conditions) together with pure hydrogen (>99.95%).The composition of the product flow is determined by gas chromatography.The conversion of ethyl benzene (EB), xylene loss and concentration ofp-xylene compared to the thermodynamic equilibrium value (p-xyleneapproach to equilibrium, PXATE) are computed: Composition of thehydrocarbon mixture (HC): Ethyl benzene (EB) 20% by weight m-Xylene 80%by weight

The test conditions and catalyst performance are summarized in Table 1.TABLE I Temp. Pressure LHSV H₂/HC (° C.) (barg) (l/l/h) mole/mole 3608.0 3.0 3.0 390 8.0 5.0 3.0 360 8.0 10.0 3.0 380 8.0 10.0 3.0 Xyleneloss Running time EB conversion (% by PXATE (hours) (% by weight)weight) (%) 360 86.1 9.0 101.6 49 95.3 8.8 101.6 293 57.9 4.4 101.8 18874.5 6.4 101.8

APPLICATION EXAMPLE 4 Use of Platinum-Free Catalyst according to Example3 for Isomerization of Xylenes

A stainless steel reactor 290 mm long with an inside diameter of 37 mmand electrical jacket heating was filled with 250 ml of the catalystfrom Example 3.

A defined hydrocarbon mixture of the composition described below isrouted over the catalyst bed according to the operating conditionsdescribed below (test conditions). The composition of the product flowis determined by gas chromatography. Test Conditions: Temperature 260°C., 280° C., 300° C. Pressure 35 barg Space velocity WHSV 10 l/l/h

The composition of the loaded hydrocarbon mixture (HC) and the productdistribution are summarized in Table II. TABLE II HC load Productdistribution (% by (% by wt.) HC name wt.) 260° C. 280° C. 300° C.Nonaromatics 0.3 0.3 0.3 0.4 Benzene 0.1 0.1 0.1 0.1 Toluene 0.4 0.6 1.11.6 EB 0.3 0.3 0.3 0.3 p-Xylene 11.4 21.5 22.7 22.6 m-Xylene 54.3 50.550.7 50.2 o-Xylene 31.3 24.6 22.4 21.8 C₉ ⁺ aromatics 1.9 2.1 2.4 3.0EB: Ethyl benzene

APPLICATION EXAMPLE 5 Use of the Catalyst according to Example 7 forDisproportionating of Toluene

A stainless steel reactor 610 mm long with an inside diameter of 19 mmand electrical jacket heating was filled with 15 ml of the catalyst fromExample 7 (diluted with 15 ml inert glass beads).

A defined hydrocarbon mixture of the composition described below ispassed over the catalyst bed according to the operating conditionsdescribed below (test conditions) together with pure hydrogen (>99.95%).The composition of the product flow is determined by gas chromatography.Test conditions: Temperature 400° C., 440° C., 480° C. Pressure 15 bargSpace velocity LHSV 0.5 l/l/h H₂/HC 3.0 mole/mole

The composition of the loaded hydrocarbon mixture (HC) and the productdistribution are summarized in Table III. TABLE III HC load Productdistribution (% by (% by wt.) HC name wt.) 400° C. 440° C. 480° C.Nonaromatics 0.0 0.1 0.1 0.0 Benzene 0.0 8.2 15.5 31.8 Toluene 99.5 80.160.3 41.2 EB 0.1 0.1 0.5 0.0 p-Xylene 0.1 2.6 5.0 5.4 m-Xylene 0.2 5.611.0 12.0 o-Xylene 0.1 2.4 5.0 5.3 Σ C₈ 0.5 10.7 21.5 22.7 C₉ aromatics0.0 0.9 2.5 3.9 C₁₀ ⁺ aromatics 0.0 0.0 0.1 0.4EB: Ethyl benzene

APPLICATION EXAMPLE 6 Use of the Catalyst according to Example 7 forTransalkylation of Substituted Aromatics

A stainless steel reactor 610 mm long with an inside diameter of 19 mmand electrical jacket heating was filled with 15 ml of the catalyst fromExample 7 (diluted with 15 ml inert glass beads).

A defined hydrocarbon mixture of the composition described below ispassed over the catalyst bed according to the operating conditionsdescribed below (test conditions) together with pure hydrogen (>99.95%).The composition of the product flow is determined by gas chromatography.Test conditions: Temperature 440° C., 480° C. Pressure 15 barg Spacevelocity LHSV 0.5 l/l/h H₂/HC 3.0 mole/mole

The composition of the loaded hydrocarbon mixture (HC) and the productdistribution are summarized in Table IV. TABLE IV HC load Productdistribution (% by (% by wt.) HC name wt.) 440° C. 480° C. Nonaromatics0.3 0.8 0.1 Benzene 0.0 14.2 15.9 Toluene 0.0 38.3 41.2 EB 0.0 1.5 1.5p-Xylene 0.0 6.6 6.6 m-Xylene 0.1 14.5 14.6 o-Xylene 0.4 6.5 6.7 Σ C₈0.5 29.1 29.4 C₉ aromatics 93.8 15.2 11.2 C₁₀ ⁺ aromatics 5.4 2.4 2.2

APPLICATION EXAMPLE 7 Use of the Catalyst according to Example 7 forConversion of Methanol into Higher Hydrocarbons

A mixture of methanol and water is converted in a 2-reactor systemconsisting of a dimethyl ether (DME) prereactor R1 and a DME conversionreactor R2 into a mixture of (water and) hydrocarbons consisting ofolefins, paraffins and aromatics. The conversion of methanol into DMEand water takes place in a DME prereactor R1 by means of an acidcatalyst, generally γ-Al₂O₃. Conversion of DME into higher hydrocarbonstakes place in the DME conversion reactor R2 over the catalyst describedin example 7.

The stainless steel reactor R1 which is 627 mm long with an insidediameter of 33.5 mm and electrical jacket heating is filled with 100 mlof commercial γ-Al₂O₃ (Sued-Chemie AG, 4.5×4.5 mm). The special steelreactor R2 which is 618 mm long with an inside diameter of 33.5 mm andelectrical jacket heating is filled with 50 ml of the catalyst fromexample 7.

A defined hydrocarbon mixture of the composition described below ispassed over the catalyst bed according to the operating conditionsdescribed below (test conditions) together with pure hydrogen(>99.996%). The composition of the product flow is determined by gaschromatography. The product distribution is summarized in Table V.Composition of the hydrocarbon/water mixture (HC): Methanol 80% byweight Water 20% by weight

Test conditions: Temperature R1 320° C. Temperature R2 300° C., 360° C.Pressure 20 barg Space velocity WHSV 2.0 g/g/h N₂/HC 9.0 mole/moleMethanol conversion >98%

TABLE V Product distribution (% by weight) HC name 300° C. 360° C. C₁-C₄36 50 C₅-C₈ (PON) 33 22 Aromatics and C₉ ⁺ 31 28 C₅ ⁺ 64 50PON: Paraffins, olefins, naphthenes

APPLICATION EXAMPLE 8 Use of the Catalyst according to Example 7 forOligomerization of Olefins

A stainless steel reactor 500 mm long with an inside diameter of 23 mmand electrical jacket heating is filled with 19 ml of the catalyst fromExample 7 (diluted with 19 ml inert glass beads).

A defined hydrocarbon mixture of the composition described below ispassed over the catalyst bed according to the operating conditionsdescribed below (test conditions) together with pure hydrogen (>99.95%).The composition of the product flow is determined by gas chromatography.Test conditions: Temperature 230° C. Pressure 75 barg Space velocityWHSV 1.0 g/g/h Running time 71 hours and 168 hours ConversionΣ_(butene) >99% by mole

The composition of the loaded hydrocarbon mixture (HC) and the productdistribution of the liquid phase are summarized in Table VI. TABLE VIProduct distribution liquid HC load phase (% by (% by wt.) HC name wt.)71 hrs 168 hrs C₁-C₃ 0.4 <C₈ 6 6 i-Butane 32.0 C₈ 12 23 n-Butane 9.0>C₈-C₁₂ 37 40 l-Butene 14.0 >C₁₂-C₁₆ 26 22 cis/trans- 29.0 >C₁₆-C₂₀ 12 7Butene i-Butene 15.0 >C₂₀ 7 2 Other 0.6

1. A process for producing synthetic zeolites with a MFI structure, aSi/Al atomic ratio of from about 8 to about 45:1 and small primarycrystallites comprising reacting a Si source, an Al source and anorganic template under hydrothermal conditions to produce a reactionproduct; wherein the process is carried out in the presence of seedcrystals of the zeolite with an average particle size from about 10 to100 nm, without separation of the seed crystals from a mother liquorproduced from an earlier synthetic zeolite production process.
 2. Theprocess of claim 1 wherein the hydrothermal reaction is accomplished ata temperature from about 100 to about 180° C.
 3. The process of claim 1wherein the concentration of the seed crystals in the reaction is fromabout 0.1 to about 0.2 percent by weight.
 4. The process of claim 1further comprising drying and calcining the reaction product.
 5. Theprocess of claim 1 further comprising converting the reaction product byion exchange into its H-form.
 6. The process of claim 1 furthercomprising producing moldings by the addition of a binder to thereaction product.
 7. The process of claim 6 wherein the binder isselected from silicic acid and aluminum hydroxide.
 8. The process ofclaim 6 wherein the binder is selected from compounds of metals selectedfrom Group III.A, III.B, IV.A, IV.B and the actinium group of theperiodic table.
 9. The process of claim 6 wherein the binder is aninorganic binder selected from the group consisting of cement, gypsumand natural silicate binders.
 10. The process of claim 6 wherein thebinder comprises an organometallic binder with a formula Me(OR)_(N) orMe(O—CO—R)_(N), wherein Me is a metal with a valency of _(N) and R is anorganic compound selected from alkyl, aryl, alkaryl and heterocycliccompounds.
 11. The process of claim 6 wherein the weight ratio of thezeolite with the MFI structure to the binder is from about 1:4 to about4:1.
 12. The process of claim 6 wherein the weight ratio of the zeolitewith the MFI structure to the binder is at least about 1:1.
 13. Theprocess of claim 1 further comprising producing moldings by the additionof catalytically active metals to the reaction product.
 14. The processof claim 1 further comprising producing moldings by the addition ofbinders and precious metal components to the reaction product.
 15. Theprocess of claim 1 wherein the Si source comprises silicic acid, the Alsource comprises sodium aluminate and the organic template comprisingtetrapropyl ammonium bromide.
 16. The process of claim 1 wherein thereaction is carried out at a pH between about 11 and
 13. 17. The processof claim 1 wherein the weight ratio of the Si source to the Al source isfrom about 2.95 to 26.5:1.
 18. The process of claim 1 wherein the atomicratio of the Si:Al in the reaction is from about 9 to about 50:1.